Protected switch



H. W. ECKLES PROTECTED SWITCH Dec. 8, 1953 Filed Feb. 25, 1950 PatentedDec. 8, 1953 UNITED STATES PATENT OFFICE Emerson Electric ManufacturingCompany, St. Louis, Mo., a corporation of Missouri Application Februaryv25, 195i), Serial No. 146,236

1 Claim. 1

Th present invention relates generally to electric switches, and moreparticularly to a starting switch for electric motors and the like whichincorporates contacts protected against fouling from dust or othermatter.

There has long been a need in the woodworking power tool art for astarting switch for the motor of such tools that will not become fouledby sawdust and the like. As is well known, a starting switch is openduring utilization of the power tool, since its function is fulfilled asthe motor reaches a predetermined speed, so, with presently usedswitches, sawdust and the like settles on the stationary and movablecontacts as the power tool is used. Hence, the contacts become fouledand do not pass current, requiring frequent cleaning. Often the contactsare seriously damaged, both electrically and through careless cleaning.

Therefore, an object of the present invention is to provide a novelswitch which incorporates protective means for the contacts.

Another object is to provide a novel switch which includes asubstantially dustproof cover or housing for the contacts constructed tomove with the movable contact including a resilient member maintainingthe same substantially sealed.

Another object is to provide a novel switch incorporating protectedcontacts which is of simplified, inexpensive, sturdy, efficientconstruction.

Other objects are to provide a novel switch incorporating protectedcontacts which reduces maintenance to a minimum, Which functionsrepeatedly and indefinitely without fouling, and which otherwisefulfills the long felt need.

The foregoing and other objects and advantages are apparent from thefollowing description taken with the accompanying drawing, in which:

Fig. 1 is a plan view of a starting switch incorporating the teachingsof the present invenof the present invention. A mounting base 12 ofinsulating material supports a stationary contact i l secured thereto byan integral rivet it, the rivet It also anchoring a stationary contactterminal E8 to the base l2.

The base l2 also supports a resilient conductive blade 20 which includesa returned mounting portion 22 anchored by rivets 23 to the base 12, adivided body portion 2G, and diverging legs 28 to the free ends of whichare secured pads 28. A terminal extension 29 is formed integral with themounting portion 22. A housing in the form of a flanged cup it issecured to the body portion 24 by an interiorly disposed movable contact32 through an integral rivet 33 so that the movable contact 32 is inopposed relation to the stationary contact M and the latter extends intothe cup 30, but is in spaced realtion to the walls thereof (Fig. 4). Aphenol resin flat washer 3 1 or the like and a metal washer 36,illustrated in the form of a cup, but which may be flat, surround thestationary contact it and are biased toward the flange of the cup to bya spiral spring 38 which also bears against the base i2. The spring 38is effective to maintain the washer 3G in substantially sealing relationwith the flange of the cup 30 at all times, a one and a half to threeounce spring having been found suitable to insure good closingengagement.

A stop member 32 limits breaking or withdrawal movement of the blade Ellthrough a T- head ts (Fig. 3). The stop member 62 is anchored to thebase I? by the rivets 23 which extend through a support portion 46, andit extends through the opening between the arms 26 of the blade 20.

Two terminal posts it and 50 are mounted on the base 12, the former ofwhich has a lead 49 soldered to the terminal 2i). A lead til connectsthe terminal post 50 with the terminal it.

In operation, as is well known, the pads 23 are engaged by a slidingsleeve indicated at 52 by broken lines to close the switch iii in thestarting of the motor with which it is associated. At a predeterminedspeed of such motor, cen trifugal force effects sliding of the sleeve 52to free the blade 20.

It is to be noted that in the closing and open" ing actions of thecontacts 32 and I l, both remain fully protected by the cup Bil andwasher 34, the latter being maintained against the former by the spring38 at all times. Sawdust and other such matter cannot reach the contacts32 and 14 to foul them. An airtight relation between the washer 34 andthe wall of the contact 3 I6 is not necessary for a continuouslyoperating starting switch, as has been demonstrated under sustainedoperating conditions.

In Fig. 5 is a modified construction which differs from that previouslydescribed in the spring elements. A spring washer 54 replaces the spring38, as does a flat metal washer 56 the cup washer 35, the spring washer54 maintaining the washer 34 in closing relation with the cup 30. Asecond flat metal washer 58 is added as support for the spring washer54.

Manifestly, there has been provided a starting switch construction whichfulfills the objects and advantages sought therefor.

It is to be understood that the foregoing description and theaccompanying drawing have been given by way of illustration and example.It is also to be understood that changes in form of the elements,rearrangement of parts, and substitution of equivalent elements, whichwill be obvious to those skilled in the art, are contemplated as withinthe scope of the present invention which is limited only by the claimwhich follows.

What is claimed is:

In an electrodynamic machine, switch construotion comprising, incombination, a base, a stationary contact supported thereon, a movableswitch blade supported thereon, a movable contact on said switch bladein opposed make and break relation to said stationary contact, a cupmember surrounding said movable contact and supported by said switchblade for movement therewith, said cup member surrounding a portion ofsaid stationary contact including its contact race, a nonconductivewasher movably disposed about the stationary contact and engaging theopen face of said cup member, a resilient metallic compression memberinterposed between said washer and said base for biasing the washercontinuously against said cup member for movement therewith, and a stopmember supported on the base for withstanding the biasing load of saidcompression member when the contacts are predeterminately separated andthereby preventing uncupping of the contact faces.

HOWARD W. ECKLES.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 473,717 Varley, Jr Apr. 26, 1892 1,313,856 Cavanagh Aug. 19,1919 1,405,537 Milton Feb. '7, 1922 2,181,586 Perryman et al Nov. 28,1939 2,192,25 Boynton Mar. 5, 1940 2,232,535 Junizen Feb. 18, 19412,339,675 Bucklen, Jr. Jan. 18, 1944 2,454,873 Hollins et a1 Nov. 20,1948 2,491,272 Knapp Dec. 13, 1949 2,520,441 Schwaneke Aug. 29, 1950

